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New Scientist Live

Zoologger: lizard’s optical illusion makes its throat fan glow up

(Image: Manuel Leal/University of Missouri)

LUMINOUS lizard lotharios ahoy! On the dark forest floors of Jamaica, male Gray anole (Anolis lineatopus) lizards use an optical illusion to make their colourful throat fans “glow” – and boost their chances of wooing a female.

The throat fans, or dewlaps, are translucent, which means they can transmit as well as reflect light. However, because most objects in the lizards’ environment – such as rocks and tree trunks – simply reflect light, our eyes “expect” all objects in the environment to appear relatively dull. By transmitting light from the background, the dewlap tricks our eyes into thinking it is actually a light source, says Leo J. Fleishman of Union College in Schenectady, New York.

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Fleishman’s team examined the photoreceptors in the lizard’s eyes to work out how they would view the dewlaps. They found that the glow significantly reduced the visual overlap, as the lizard’s eyes would experience it, between the throat fans and the colours of natural backgrounds.

Fleishman thinks that the dewlaps help lizards to communicate more clearly and efficiently – to gain a mate during breeding season and perhaps to warn off rivals or predators, too (Functional Ecology, doi.org/6br).

This article appeared in print under the headline “Optical illusion lets lizards glow”